1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2011-2017 Red Hat, Inc.
4 *
5 * This file is released under the GPL.
6 */
7
8#ifndef DM_BIO_PRISON_V2_H
9#define DM_BIO_PRISON_V2_H
10
11#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
12#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
13
14#include <linux/bio.h>
15#include <linux/rbtree.h>
16#include <linux/workqueue.h>
17
18/*----------------------------------------------------------------*/
19
20int dm_bio_prison_init_v2(void);
21void dm_bio_prison_exit_v2(void);
22
23/*
24 * Sometimes we can't deal with a bio straight away. We put them in prison
25 * where they can't cause any mischief. Bios are put in a cell identified
26 * by a key, multiple bios can be in the same cell. When the cell is
27 * subsequently unlocked the bios become available.
28 */
29struct dm_bio_prison_v2;
30
31/*
32 * Keys define a range of blocks within either a virtual or physical
33 * device.
34 */
35struct dm_cell_key_v2 {
36 int virtual;
37 dm_thin_id dev;
38 dm_block_t block_begin, block_end;
39};
40
41/*
42 * Treat this as opaque, only in header so callers can manage allocation
43 * themselves.
44 */
45struct dm_bio_prison_cell_v2 {
46 // FIXME: pack these
47 bool exclusive_lock;
48 unsigned int exclusive_level;
49 unsigned int shared_count;
50 struct work_struct *quiesce_continuation;
51
52 struct rb_node node;
53 struct dm_cell_key_v2 key;
54 struct bio_list bios;
55};
56
57struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq);
58void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison);
59
60/*
61 * These two functions just wrap a mempool. This is a transitory step:
62 * Eventually all bio prison clients should manage their own cell memory.
63 *
64 * Like mempool_alloc(), dm_bio_prison_alloc_cell_v2() can only fail if called
65 * in interrupt context or passed GFP_NOWAIT.
66 */
67struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison,
68 gfp_t gfp);
69void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
70 struct dm_bio_prison_cell_v2 *cell);
71
72/*
73 * Shared locks have a bio associated with them.
74 *
75 * If the lock is granted the caller can continue to use the bio, and must
76 * call dm_cell_put_v2() to drop the reference count when finished using it.
77 *
78 * If the lock cannot be granted then the bio will be tracked within the
79 * cell, and later given to the holder of the exclusive lock.
80 *
81 * See dm_cell_lock_v2() for discussion of the lock_level parameter.
82 *
83 * Compare *cell_result with cell_prealloc to see if the prealloc was used.
84 * If cell_prealloc was used then inmate wasn't added to it.
85 *
86 * Returns true if the lock is granted.
87 */
88bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
89 struct dm_cell_key_v2 *key,
90 unsigned int lock_level,
91 struct bio *inmate,
92 struct dm_bio_prison_cell_v2 *cell_prealloc,
93 struct dm_bio_prison_cell_v2 **cell_result);
94
95/*
96 * Decrement the shared reference count for the lock. Returns true if
97 * returning ownership of the cell (ie. you should free it).
98 */
99bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
100 struct dm_bio_prison_cell_v2 *cell);
101
102/*
103 * Locks a cell. No associated bio. Exclusive locks get priority. These
104 * locks constrain whether the io locks are granted according to level.
105 *
106 * Shared locks will still be granted if the lock_level is > (not = to) the
107 * exclusive lock level.
108 *
109 * If an _exclusive_ lock is already held then -EBUSY is returned.
110 *
111 * Return values:
112 * < 0 - error
113 * 0 - locked; no quiescing needed
114 * 1 - locked; quiescing needed
115 */
116int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
117 struct dm_cell_key_v2 *key,
118 unsigned int lock_level,
119 struct dm_bio_prison_cell_v2 *cell_prealloc,
120 struct dm_bio_prison_cell_v2 **cell_result);
121
122void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
123 struct dm_bio_prison_cell_v2 *cell,
124 struct work_struct *continuation);
125
126/*
127 * Promotes an _exclusive_ lock to a higher lock level.
128 *
129 * Return values:
130 * < 0 - error
131 * 0 - promoted; no quiescing needed
132 * 1 - promoted; quiescing needed
133 */
134int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
135 struct dm_bio_prison_cell_v2 *cell,
136 unsigned int new_lock_level);
137
138/*
139 * Adds any held bios to the bio list.
140 *
141 * There may be shared locks still held at this point even if you quiesced
142 * (ie. different lock levels).
143 *
144 * Returns true if returning ownership of the cell (ie. you should free
145 * it).
146 */
147bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
148 struct dm_bio_prison_cell_v2 *cell,
149 struct bio_list *bios);
150
151/*----------------------------------------------------------------*/
152
153#endif
154

source code of linux/drivers/md/dm-bio-prison-v2.h